Electrokinetic conditioning of foundation piles

ABSTRACT

A method for increasing load capacity of a foundation pile installed in a ground material is described. At least one electrode is embedded in the ground material at a predetermined distance from the installed pile. A direct current power source is provided, with the power source including at least one cathode connection and at least one anode connection. One of the at least one cathode connection is secured to the foundation pile. One of the at least one anode connections is secured to each of the at least one electrodes. The direct current power source is activated to generate an electric gradient between the foundation pile and the at least one electrode, with the electric gradient being selected to direct charged soil particles in the ground material toward the foundation pile.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/417,980, entitled “INCREASING CAPACITY ANDENHANCEMENT SET-UP OF STEEL PILES IN CLAY SOIL BY ELECTROKINETIC METHOD”and filed Nov. 30, 2010, the entire disclosure of which is incorporatedherein by reference, to the extent that it is not conflicting with thepresent application.

BACKGROUND

Pile foundations are used for the support of heavy structures, such asbridges, tall buildings, and the like. A significant increase in theload capacity of these piles is often observed over time after initialinstallation, and is generally attributed to consolidation of cohesiveground materials, such as clay and cohesive soils, around the pile afterpile installation, and dissipation of water pressure around the piles.This time-dependent strength gain is commonly referred to as “set-up,”and may be tested by “re-strikes” of the piles, measuring thedisplacement of the pile as the result of application of a known force.While formulas have been developed to estimate pile capacity as afunction of elapsed time after installation, these formulas may not berelied upon in subjecting the piles to loads during construction. Assuch, the construction of pile foundations often requires a waitingperiod after installation of the piles for a sufficient increase in loadcapacity. Further, the pile capacities are often not utilized to theirfull potential as construction often relies upon capacities that aremeasured, for practical reasons and safety considerations, after severaldays to a few weeks from installation when only a fraction of set-up hasoccurred, for example, to minimize construction delays.

SUMMARY

The present application describes systems and methods for acceleratingor increasing set-up of an embedded structure (e.g., a steel foundationpile) by generating an electrical polarity at the embedded member thatis opposite an inherent electrical polarity of a cohesive groundmaterial into which the structure is embedded, such that the cohesiveground material is attracted to or adhered to the embedded structure. Inone such exemplary embodiment, a positive electrical polarity isgenerated at a steel foundation pile to attract cohesive clay soilparticles having a net negative surface charge.

The present application also describes systems and methods forfacilitating removal of an embedded structure (e.g., a steel foundationpile) by generating an electric polarity at the embedded member that isthe same as an inherent electrical polarity of a cohesive groundmaterial into which the structure is embedded, such that the cohesiveground material is dispersed or repelled from the conductive member,thereby reducing ground material adhesion to the embedded conductivemember for reduced resistance to pull-out.

Still other advantages, aspects, and features of the present applicationwill become readily apparent to those skilled in the art from thefollowing description, wherein there is shown and described an exemplaryembodiment of the present application. As it will be realized, thepresent application is capable of other different embodiments, and itsseveral details are capable of modifications in various aspects, allwithout departing from the scope of the present application.Accordingly, the drawings and descriptions will be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become apparent from the followingdetailed description made with reference to the accompanying drawings,wherein:

FIG. 1 is a schematic illustration of a system for electrokineticconditioning of an embedded structure, according to an exemplaryembodiment;

FIG. 2A is an illustration of an exemplary mold for preparing a soilsample for bench scale pile set-up testing;

FIG. 2B is an illustration of an exemplary hammer arrangement for abench scale pile set-up test;

FIG. 3 illustrates a graph of load required for a 3 mm penetrationversus time, as tested in Example I below;

FIG. 4 illustrates a graph showing load versus electric gradientapplication duration, as tested in Example I below;

FIG. 5 is a schematic illustration of an exemplary pile drivingarrangement;

FIG. 5A is an enlarged view of the pile from the pile drivingarrangement of FIG. 5;

FIGS. 6-9 graphically illustrate the difference in pile capacitiesbetween electrokinetically conditioned soil samples exposed to anelectric gradient of 30 Volts DC per foot and substantially identicalsoil samples not subjected to an electric gradient, as tested in ExampleII below; and

FIG. 10 graphically illustrates the difference in pile capacitiesbetween substantially identical clay soil samples exposed to differentamounts of applied electric gradient, as tested in Example II below.

DETAILED DESCRIPTION

The Detailed Description merely describes exemplary embodiments of theinvention and is not intended to limit the scope of the claims in anyway. Indeed, the invention is broader than and unlimited by theexemplary embodiments, and the terms used in the claims have their fullordinary meaning

Also, while the exemplary embodiments described in the specification andillustrated in the drawings relate to installation and removal of steelfoundation piles, it should be understood that many of the inventivefeatures described herein may be applied to installation and removal ofother ground embedded structures, such as posts, spikes, and plates.

Installation or driving of foundation piles into cohesive soil, such asclay-based soil, generally causes the soil around the driven pile toundergo plastic deformation and to develop increased pore water pressurearound the driven pile, both of which may contribute to an initialreduced or limited load capacity of the pile. After the pile driving orinstallation is completed, excess pore pressure around the driven piletends to dissipate, and the cohesive soil tends to re-consolidate aroundthe driven pile, resulting in increases in the load capacity of thedriven pile over time. However, due to variations in soil conditions,both between the locations of multiple piles employed in a singleconstruction product, and across multiple soil strata into which asingle pile is driven, set-up of a conventionally installed pile mayvary, and in some cases, little or no set-up may occur, or even arelaxation or loss of load capacity may occur over time. Thisvariability in set-up has conventionally required significant waitingperiods to verify sufficient load capacity of the driven piles, and todetermine the number of piles required to support the eventual load.Further, due to the long periods of time over which natural set-up mayoccur, and the prohibitive costs and inconveniences of substantialconstruction delays, construction projects are often unable to takeadvantage of this long-term strength gain, and redundant piles aredriven during construction to satisfy load capacity requirements afteronly a minimal waiting period.

The present application contemplates methods and systems of improvingload capacity or set-up of a ground embedded structure, such as a steelfoundation pile, by applying an electric gradient between the embeddedstructure and the surrounding soil. Without being bound by theory,applicant believes that this application of an electrical gradientbetween the embedded structure and a clay-based surrounding soilgenerates an electrochemical attraction between charged soil particlessurrounding the embedded structure and the oppositely charged embeddedstructure. In the case of clay-based soils, the inherent negativesurface charge of the clay particles facilitates electrochemicalattraction to a positively charged structure. In some applications,moisture collected in the soil around the embedded structure allows fora phenomenon known as electrophoresis, in which an electrical fieldapplied to the water creates an electric gradient between the soil andthe embedded structure, causing charged clay particles to migratethrough the water and toward the embedded structure. Adherence of theseclay particles to the embedded foundation pile creates a clay plugsurrounding the pile, increasing the effective diameter of the pile,resulting in an increased shaft resistance of the pile.

While many different arrangements may be utilized to apply an electricgradient between an embedded structure (e.g., an installed foundationpile) and the surrounding soil, in one embodiment, as shownschematically in FIG. 1, one or more electrodes 20 may installed orembedded into the soil S around the embedded structure 10, and anelectrical potential gradient may be generated between the embeddedstructure and each of the one or more installed electrodes. In one suchembodiment, a direct current power source 30 includes an adjustabledirect current power supply (e.g., an Acopian AC to DC Power Supply,model no. U24Y2300), for example, to allow for a user selected voltage.A positive terminal 31 of the direct current power source 30 may beconnected directly to the embedded structure (for example, using aconductive clamp, such as a mini-clip or gator clip), and one or morenegative terminals 32 (e.g., branched terminals) of the direct currentpower source 30 may be connected directly to each of the embeddedelectrodes 20. The direct current power source 30 may then be activatedand adjusted to apply a constant selected direct current voltage,thereby generating the desired electrokinetic field between the embeddedstructure 10 and the surrounding soil S. In other embodiments, forexample, where the embedded structure is not itself conductive,additional electrodes may be embedded in the surrounding soil in contactwith or in close proximity with the embedded structure, such thatattachment of positive terminals to these proximate electrodes may serveto attract clay (or other negatively charged) cohesive soil particlestoward the embedded structure, and to repel water molecules from theembedded structure.

While not intending to be bound by theory, applicant believes that theapplication of a low-intensity direct current through thewater-saturated soil surrounding an installed foundation pile mobilizesnegatively charged clay particles or colloids C (e.g., kaolinite,illite, montmorillonite, and chlorite clays) to cause the clay colloidsto move toward the positively charged pile (or toward positively chargedelectrodes proximate the pile), a phenomenon referred to aselectrophoresis. At the same time, neutral or net positive charged watermolecules W are mobilized to disperse from the surface of the pile andflow toward the surrounding negative electrodes, a phenomenon referredto as electroosmosis. The effects of these two simultaneous phenomenainclude an increase in soil density around the pile, a decrease in watercontent and pore pressure around the pile, the formation of a clay plugaround the pile, effectively increasing the effective diameter of thepile, and an increase in shaft resistance due to this increasedeffective diameter. All of these effects are believed to increase oraccelerate set-up of the installed pile, as compared to the naturalexpected set-up of the pile in the absence of an applied electrokineticfield.

Many factors involving an installed foundation pile and the conditionsof the surrounding soil may affect the amount of set-up experienced bythe pile, including, for example, pile length, pile diameter, soilconditions (including materials, cohesiveness, and moisture content),elapsed time, and vibrations during pile driving (which may producecapacity impairing cracks in clay or other cohesive soil materials)

In an exemplary steel foundation pile installation and conditioningapplication, a stainless steel foundation pile having a diameter ofapproximately 12-24 inches and a length of approximately 40-150 ft. isembedded in clay based ground soil. Three electrodes (e.g., stainlesssteel rods) having a diameter of approximately 1-2 inches and a lengthof approximately 25 ft. (or at least about half the length of the pile)are embedded in the surrounding soil at a distance from the pile ofapproximately 3-6 feet and evenly spaced from each other. An adjustabledirect current power source is provided, with a positive terminalconnected to the pile, and branched negative terminals connected to eachof the electrodes. The power source is operated to deliver a voltage ofapproximately 100-300 V DC, to provide a gradient of approximately 1-30V/ft between the pile and the electrodes. This voltage is maintained fora predetermined period, for example, at least 24-48 hours, before astatic or dynamic load capacity test is employed to verify thatsufficient set-up has occurred to support the structure to be built onthe pile or piles.

According to another aspect of the present application, electrokineticconditioning of an embedded structure, such as a foundation pile, may beutilized to loosen the embedded structure, for example, to remove orreposition the embedded structure. In such an application, an electricgradient opposite of the electric gradient described above may beapplied, with a negative charge applied to the embedded structure and apositive charge applied to one or more embedded electrodes surroundingthe embedded structure. While not intending to be bound by theory,applicant believes that the application of a low-intensity directcurrent through the water saturated soil surrounding an installed steelfoundation pile, with a negative charge applied to the pile, mobilizesnegatively charged clay colloids to cause the clay colloids to move awayfrom the negatively charged pile and toward the positively chargedelectrodes. At the same time, neutral or net positive charged watermolecules are mobilized to migrate toward the surface of the pilefurther reducing the shaft resistance of the pile. The effects of thesetwo simultaneous phenomena are believed to include a reduction in soildensity around the pile, an increase in water content and pore pressurearound the pile, and a resulting decrease in pile shaft resistance. Allof these effects are believed to loosen the installed pile, therebyfacilitating removal or repositioning of the pile within the groundsoil.

EXAMPLE I Preliminary Testing

Preliminary bench scale tests were conducted on two pile-clay specimens.The material specifications for the preliminary tests are given in Table1.

TABLE 1 Specifications of Materials used during Preliminary Tests ItemMaterial Dimensions/Weight Manufacturer Pile Stainless Hollow pipeSpee-D-Metals, Steel Length = 9 in., Thk = 0.42 in. Cleveland, OH. OD is1 in. for a length of 3 in. and 0.5 in. for the remaining 6 in. SoilKaolinite 50 lb bag Feldspar Clay Corporation, Atlanta, GA ElectrodeStainless Solid ¼ inch dia. rods Machine Steel Shop, CSU

The procedure followed in preparing the kaolinite sample was similar tothe one for Standard Proctor Test, ASTM D-698. The soil was compacted ina mold with a diameter of 4 inches and a height of 6.5 inches (includingthe collar). The soil was mixed with 34% by weight water and thencompacted in four equal layers by a hammer that delivered 25 blows toeach layer. The hammer had a mass of 2.5 kg (5.5 lb) and a drop of 12inches. FIGS. 2A and 2B illustrates the exemplary mold 40 and hammer 50,respectively, that were used. The 1 inch diameter stainless steel pilewas then driven into the center of the clay sample by lightly tappingthe sample.

Care was taken during pile driving to avoid the formation of vibrationcracks in clay. The mold was then covered with a rubber pad to preventmoisture loss due to evaporation. The specimen was then kept in acovered tub partially filled with water. This arrangement was helpful inmaintaining the moisture content of the soil sample throughout thetesting period.

The two specimen to be tested were statically loaded using a tri-axialtesting machine (model #, supplier) on Days 0, 1, 3, 8, 16, 22, 31 and46 after the end of initial driving. A rapid moisture content test(e.g., OHAUS, MB 200) was conducted prior to each static load test. Anelectric gradient of 30 Volts DC/ft was applied to Specimen A, betweenstatic load tests, Day 3 onwards.

Two kaolinite clay-steel pile specimen were prepared in accordance withthe method explained above. Laboratory testing was then performed usinga preliminary test program. The two specimens to be tested werestatically loaded using the tri-axial testing machine on Days 0, 1, 3,8, 16, 22, 31 and 46 after the end of initial driving. A rapid moisturecontent test was conducted prior to each static load test. An electricgradient of 30 Volts DC/ft was applied to Specimen A, between staticload tests, from Day 3 onwards. Static load test results are presentedin tabular and graphical form below.

Load versus penetration data taken on all test days is presented inTable 2. Specimen A was subjected to an electric gradient of the orderof 30 Volts DC/ft between test days, starting from Day 3. Becausespecimen B was not connected to any voltage source, it was allowed toachieve set-up as a natural process.

As shown in Table 2, at day 3, pile capacities of both specimens werealmost identical (239 N for Spec A and 244 N for Spec B). It can be seenfrom these graphs that from Day 3 onwards, there were substantialincreases in the pile static capacity values of Specimen A as comparedto Specimen B. An electric gradient of 30 Volts DC/ft was applied toSpecimen A for a duration of 100 hours between Day 3 and Day 8. Theresulting pile capacity values at the end of Day 8 were 693 N and 293 Nfor Specimens A and B, respectively. Further application of the electricgradient to Specimen A for a cumulative duration of 443 hours resultedin capacities of 1937 N for Specimen A (compared to 419 N for SpecimenB) at the end of Day 31. FIG. 3 shows a graph of load required for a 3mm penetration versus time. A graph showing load versus electricgradient application duration is shown in FIG. 4.

The moisture contents of both specimens were approximately 34% at thebeginning of the testing sequence, and showed a variation ofapproximately ±5% during the course of the testing period.

Results obtained from preliminary tests confirmed the feasibility of theresearch proposal and paved the way for more extensive research.Specimen A, after being subjected to an electric gradient of 30 V DC/ftfor a duration of 100 hours, gained pile capacity 9 times greater thanthe pile capacity of Specimen B, which was allowed to achieve naturalset-up. Moisture contents of Specimens A and B did not altersubstantially during the course of the testing period.

TABLE 2 Load versus penetration data obtained on all tests days Load in‘N’ DAY Dis 0 1 3 8 16 22 31 46 ‘mm’ A B A B A B A B A B A B A B A B 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 85 151 143 176 197 210 702 229 1126 2651218 303 1521 387 819 429 2 108 171 185 199 218 228 713 243 1164 2791201 315 1933 405 1558 466 3 127 185 203 210 227 235 693 249 1155 2861226 324 1918 412 1789 489 4 143 195 216 218 235 239 251 293 1937 4192029 508 5 157 206 225 223 239 244 6 169 216 231 227 7 179 223 237 231 8190 231

EXAMPLE II Extended Testing

Further, expanded bench scale testing was also performed, using twentysoil samples, designated P1 through P20, of varying clay content,moisture content, and electrokinetic field conditions, as shown in Table3 below:

TABLE 3 Test program details Clay Moisture D.C. Voltage Specimen Content(%) Content (%) (Volts) P1 50 35 0 P2 50 35 0 P3 50 35 30 P4 50 35 30 P525 12 0 P6 25 12 30 P7 25 17 0 P8 25 17 30 P9 100 40 0 P10 100 40 0 P11100 40 1 P12 100 40 1 P13 100 40 10 P14 100 40 30 P15 100 40 30 P16 10040 10 P17 100 35 0 P18 100 35 0 P19 100 35 30 P20 100 35 30

Static load tests were scheduled to be conducted on days 0, 1, 3, 7, 14,21, 35, 42, 49, 56 and 63. Specimens P1-P8 constituted soil samplescontaining a mixture of sand and kaolinite clay having the clay contentidentified in Table 3, while specimens P9-P20 were formed entirely fromkaolinite clay. DC voltages applied to the respective samples betweenstatic load tests, as identified in Table 3, began on day 3 of the test.The test program was developed to compare the pile capacity valuesbetween: (a) specimens subjected to electric gradient versus those thatare not; (b) specimens subjected to different DC potential values; (c)specimens with different clay content; and (d) specimens with differentmoisture content.

The specifications for all other materials used in the testing are givenin Table 4.

TABLE 4 Specifications of Materials Item Material Dimensions/WeightManufacturer Pile Stainless Solid pipe Spee-D-Metals, Steel Length =14.65 in. Cleveland, OH. Top 8 inches: ½ dia. Middle 6 inches: ¾ dia.Bottom solid cone: ¾ dia., 0.65 ht Soil Kaolinite 50 lb bag FeldsparClay Corporation, Atlanta, GA Sand 50 lb bag Silica sand #1 ElectrodeStainless Solid 14 inch long, ¼ inch dia. Machine Steel rods Shop, CSU

The aspect ratio, or the ratio of length of the pile to the diameter ofthe pile, was increased by increasing the test length of the pile from 3inches to 6 inches and reducing its diameter from 1 in. to ¾ in. A solidstainless steel pipe section with a solid conical bottom as waspreferred over the earlier hollow pipe to eliminate plugging effect orend face resistance of the soil sample. The conical shape of the base ofthe pile was selected to minimize the effect of the end face resistanceof the pile. Additionally, the use of a solid pile in place of a hollowpile was intended to eliminate the effects of resistance against aninner surface of a hollow pile. Twenty such pile segments weremanufactured at Spee-D-Metals in Cleveland, Ohio.

The procedure followed to prepare the soil sample was similar to the onefor Standard Proctor Test, ASTM D-698. The soil was compacted in a PVCmold with a diameter of 6 inches and a height of 12 inches. Due to theadditional height of the mold, the specimens could be tested over alonger period of time resulting in more experimental data.

Twenty soil samples with different sand-clay proportions and moisturecontents were prepared on the basis of the test plan, as discussed aboveand shown in Table 3. The soil was mixed with the appropriate percentageby weight of water and then compacted in four equal layers by a hammerthat delivered 25 blows to each layer. The hammer had a mass of 2.5 kg(5.5 lb) and a drop of 12 inches.

During preliminary testing, piles were driven into the soil sample bylightly tapping the pile head. To make the driving sequence more uniformfor the extended testing, a pile driving arrangement was constructed.FIG. 5 shows a schematic diagram of the manually operated pile drivingarrangement 100, which includes a solid platform base 120 and a hammer130 and collar assembly. The platform functioned to hold the soil samplein place during the event of driving. The hammer and collar assembly wasarranged to achieve correct pile alignment and uniform pile driving.

During the design and construction of the pile driving arrangement, anappropriate weight, size and length for the hammer ram were determinedby a trial and error method. The design of the collar was dependant onthe size and weight of the ram. The purpose of the collar was to avoidsimultaneous movement of the ram and the pile, while the ram was raisedto a known drop height. So it had to act like a separator between theram and the pile. At the same time, the collar had to be always incontact with the pile and move with it during the entire event ofdriving. The soil specimen, the pile, and the hammer and collararrangement had to maintain individual as well as relative positionsduring the driving sequence to obtain an accurate pile alignment anduniform driving. This was achieved by constructing a support framestructure fabricated from solid steel rods and metal plates.

In installing the piles, the hammer ram was manually raised to a fixeddrop height using a rope and pulley assembly, and released so that itfell under the influence of gravity. Several blows were needed to drivethe pile six inches into the ground. The amount of energy needed todrive the pile was recorded, in the form of the hammer weight, number ofblows and the drop height. The weight of the hammer ram was constant andapproximately equal to 1.7 kg (3.75 lbs). Accordingly, a drop height of3 inches induced an energy in the amount of 0.94 lb-ft for each hammerblow.

In preparing for the test, twenty ¾ inch diameter stainless steel piles110 (as shown in FIG. 5A) were driven into the center of soil samplesprepared earlier, thus creating twenty soil-pile specimens ready fortesting. The day on which the piles were driven was termed as Day 0 onthe time log. Day 0 can also be defined as the day that marks thecompletion of the end of initial drive (EOID) event, a term which is awidely used in pile driving. Three ¼ inch diameter solid stainless steelrods with an approximate length of 14 inches were driven into thosespecimens which were going to be subjected to an electric gradient.These rods were equally spaced around the pile and at approximately 1.5inches from the pile surface, or about 2 inches from the center of themold.

These steel pile-clay specimens were covered with plastic secured by arubber band at all times to minimize the effect of loss of moisturecontent due to evaporation. The specimens were stored in an aluminumwater tank between testing events to reduce moisture losses due toevaporation. The tank was partially filled with water and covered with athick polythene cover.

A rapid moisture content test was conducted on every specimen on alltest days before performing a static load test, using an OHAUS MB 200moisture analyzer. The rapid moisture content detector oven dried a soilsample in approximately 15 minutes (as compared to a 16 to 24 hourdrying time in case of a regular moisture content determination test),and displayed the absolute value of the moisture content in terms of apercentage on a LCD screen. The moisture content test was performed inaccordance with ASTM D4959.

The specimens to be tested were statically loaded using a tri-axialtesting machine (e.g., an ELE Tri-axial Testing System). The tri-axialmachine includes a hydraulic loading platform to which a load cell andpenetrometer are attached. The load cell and penetrometer are connectedto a computer which is programmed to dynamically read, tabulate and plotthe load versus penetration graph for each specimen.

The static load test was performed in accordance with ASTM D-1143 with aminor variations to account for use of a tri-axial testing machineinstead of a conventional axial compressive loading device.

To generate an electrokinetic field between the piles and thesurrounding electrodes, a positive terminal of a direct current voltagesource was connected to the pile, and negative terminals of the voltagesource were connected to each of the three electrodes. The DC voltagesource applied a constant voltage across the specimen for the durationof the test period. The test program requirement made it mandatory thatat least three voltage sources, which could apply 1V, 10 V and 30 V ondifferent specimens, be used simultaneously. A log was maintained torecord the durations of application of electric gradient.

The temperature of each of the specimens was monitored on a regularbasis, including during the application of electric gradient. A labthermometer was used to record temperatures.

The twenty soil-pile specimens of varying clay content, moisturecontent, and eletrokinetic field exposure were subjected to static loadtesting on days 0, 1, 3, 7, 14, 21, 28, 252, and 256, as measured fromthe end of initial driving. (Static load testing was terminated duringtesting on Day 42 due to technical problems with the load cell used inthe tri-axial testing machine). The application of electrokinetic fieldsto the specimens was carried out from Day 3 to Day 42, with only brieftermination of the electrokinetic fields during static load testing.

Test data taken on Days 0, 1, 3, 7, 14, 21, 28, 42 (partial), 252 and256 are presented in Tables 6-15 respectively. Static load tests wereterminated at the point when the specimens shows no further signs ofincrease in load for two or three consecutive increments of pilepenetration. The maximum stable load attained by each specimen on alltest days is tabulated in Table 16.

TABLE 5 Specimen Information PILE SET-UP EXPERIMENTAL DATA PILE SET-UPEXPERIMENTAL DATA P1 P2 P3 P4P 5P 6P 7P 8 P9 10 P11 P12 P13 P14 P15 P16P17 P18 P19 P20 Mois. Con. 35 35 35 35 12 12 17 17 40 40 40 40 40 40 4040 35 35 35 35 DC Volt 0 0 30 30 0 30 0 30 0 0 1 1 10 30 30 10 0 0 30 30% Sand 50 50 50 50 75 75 75 75 0 0 0 0 0 0 0 0 0 0 0 0 # Blows 0 0 0 1010 65 0 8 63 102 80 123 177 110 110 147 438 300 336 325

TABLE 6 Load versus penetration data taken on Day 0 Day 0 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 10 11 21 27 24 130 2 6 67 132 74 99 128 128 116 105 326 282244 242 2 11 11 23 31 41 147 2 6 74 137 85 104 128 129 127 120 330 291250 258 3 11 11 23 32 47 155 2 6 78 141 90 104 128 128 130 128 332 296250 267 4 32 50 160 2 8 82 141 92 111 132 132 333 296 250 274 5 55 16410 82 142 95 111 136 134 334 300 279 6 55 167 11 97 137 137 300 288 7172 11 99 137 292 8 176 11 99 300 9 11 307 10 313 Day 0 11 11 23 32 55176 2 11 82 142 99 111 128 128 137 137 334 300 250 313

TABLE 7 Load versus penetration data taken on Day 1 Day 1 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 10 11 21 27 24 130 2 6 67 132 74 99 128 128 116 105 326 282244 242 2 11 11 23 31 41 147 2 6 74 137 85 104 128 129 127 120 330 291250 258 3 11 11 23 32 47 155 2 6 78 141 90 104 128 128 130 128 332 296250 267 4 32 50 160 2 8 82 141 92 111 132 132 333 296 250 274 5 55 16410 82 142 95 111 136 134 334 300 279 6 55 167 11 97 137 137 300 288 7172 11 99 137 292 8 176 11 99 300 9 11 307 10 313 Day 1 11 11 23 32 55176 2 11 82 142 99 111 128 128 137 137 334 300 250 313

TABLE 8 Load versus penetration data taken on Day 3 Day 3 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 25 29 43 48 84 200 4 20 113 168 126 134 139 148 164 176 324345 284 408 2 25 29 42 46 89 206 5 21 113 168 130 134 139 147 164 176329 345 284 416 3 25 29 42 46 92 210 6 21 113 130 134 139 147 162 176332 345 284 420 4 92 210 6 334 426 5 6 335 433 6 438 7 8 9 10 Day 3 2529 42 46 92 210 6 21 113 168 130 134 139 147 162 176 335 345 284 438

TABLE 9 Load versus penetration data taken on Day 7 Day 7 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 25 31 252 231 115 1244 4 355 126 178 138 143 139 307 345 190292 357 521 647 2 25 29 244 235 118 1611 4 349 126 176 134 143 139 287340 190 328 357 584 660 3 25 29 244 239 118 1773 4 345 126 176 134 143141 274 336 190 332 357 562 649 4 234 1800 6 345 142 333 542 641 5 8 142334 534 6 8 7 8 9 10 Day 7 25 29 244 234 118 1800 8 345 126 176 134 143142 274 336 190 334 357 534 641

TABLE 10 Load versus penetration data taken on Day 14 Day 14 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 26 34 265 227 142 2515 4 328 139 197 160 163 155 248 370 214345 378 498 613 2 25 34 263 218 143 2521 4 336 139 193 159 160 155 248366 210 349 374 504 618 3 25 34 263 212 146 4 333 139 193 157 160 155248 357 207 352 371 504 617 4 206 148 5 340 155 353 206 353 370 5 205151 6 155 349 6 155 8 345 7 160 8 8 164 9 168 10 172 Day 14 25 34 263205 172 2521 8 340 139 193 155 160 155 248 345 206 353 370 504 617

TABLE 11 Load versus penetration data taken on Day 21 Day 21 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 34 42 261 286 8 500 151 206 191 197 239 454 737 500 340 378728 1052 2 29 38 265 264 8 479 147 202 189 192 227 454 765 384 342 378739 1064 3 29 38 269 252 12 471 147 199 188 189 223 445 739 370 345 378705 1038 4 265 253 12 458 197 185 189 218 436 708 358 345 689 1000 5 25010 478 193 185 218 432 674 352 695 963 6 479 193 429 648 345 697 947 7424 628 344 929 8 420 914 9 10 Day 21 29 38 265 250 10 479 147 193 185189 218 420 628 344 345 378 697 914

TABLE 12 Load versus penetration data taken on Day 28 Day 28 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 29 41 374 563 202 2596 8 643 164 214 239 235 345 412 571 416353 395 685 1014 2 29 38 387 450 207 2550 8 622 160 212 234 231 328 416601 419 355 395 653 1017 3 29 38 369 352 210 2555 8 626 160 209 231 227315 429 606 416 357 395 647 1029 4 366 334 211 2550 12 643 206 227 227315 437 606 357 651 1038 5 333 214 647 206 227 434 639 1021 6 218 437639 1017 7 218 639 1017 8 9 10 Day 28 29 38 366 333 218 2550 12 647 160206 227 227 315 437 606 416 357 395 638 1017

TABLE 13 Load versus penetration data taken on Day 42 Day 42 Load in ‘N’Disp ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17 P18P19 P20 1 42 46 626 782 8 2 42 46 647 739 8 3 42 46 647 706 11 4 660 135 660 13 6 14 7 17 8 9 10 Day 42 42 46 647 660 17

TABLE 14 Load versus penetration data taken on Day 252 Day 252 Disp Loadin ‘N’ ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17P18 P19 P20 1 126 108 717 754 940 3627 45 1176 369 462 524 571 866 811960 564 580 567 874 991 2 121 105 730 743 876 3693 47 1199 362 440 534588 856 839 903 700 574 556 977 1174 3 121 100 717 736 850 3744 50 1212359 420 565 588 854 861 886 721 570 545 992 1241 4 99 703 728 823 377753 1223 357 401 570 852 875 886 735 566 540 1041 1200 5 99 690 700 8243832 53 1271 357 389 580 850 882 742 566 537 1071 1200 6 690 700 38541310 378 580 848 900 740 537 1112 7 3927 1341 368 847 900 1163 8 39541341 359 847 1192 9 4000 351 1212 10 4069 351 1212 Day 121 99 690 700824 4517 53 1341 357 351 580 588 847 900 886 740 566 537 1212 1200 252

TABLE 15 Load versus penetration data taken on Day 256 Day 256 Disp Loadin ‘N’ ‘mm’ P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 P16 P17P18 P19 P20 1 131 105 646 720 1013 3076 50 1348 386 402 686 645 647 697782 582 563 550 1054 1053 2 126 101 683 728 998 3775 57 1481 386 393 694646 700 753 869 869 569 557 1144 1134 3 126 100 693 741 982 3854 59 1535378 669 643 730 807 928 703 570 557 11367 1154 4 100 693 708 977 3917 631587 372 650 643 752 845 987 760 575 557 1196 1180 5 708 965 3929 661586 364 650 767 873 1000 760 578 1239 1209 6 956 4003 68 1586 361 782903 1000 583 1264 1225 7 945 4001 72 360 801 924 588 1264 1221 8 9454006 74 357 817 943 588 1222 9 4060 84 361 851 960 10 4100 84 361 851960 Day 126 100 693 708 945 4620 84 1596 386 361 650 643 851 960 1000760 588 557 1264 1222 256

TABLE 16 Summary of Maximum Stable Loads on all Test Days Maximum StableLoad in ‘N’ Day P1 P2 P3 P4P 5P 6P 7P 8 P9 10 P11 P12 P13 P14 P15 P16P17 P18 P19 P20 0 11 11 23 32 55 176 2 11 82 142 99 111 128 128 137 137334 300 250 313 1 15 19 32 37 71 193 2 15 95 153 107 117 128 132 145 153334 326 276 397 3 25 29 42 46 92 210 6 21 113 168 130 134 139 147 162176 335 345 284 438 7 25 29 244 234 118 1800 8 345 126 176 134 143 142274 336 190 334 357 534 641 14 25 34 263 205 172 2521 8 340 139 193 155160 155 248 345 206 353 370 504 617 21 29 38 265 250 10 479 147 193 185189 218 420 628 344 345 378 697 914 28 29 38 366 333 218 2550 12 647 160206 227 227 315 437 606 416 357 395 638 1017 42 42 46 647 660 17 252 12199 690 700 824 4517 53 1341 357 351 580 588 847 900 886 740 566 537 12121200 256 126 100 693 708 945 4620 84 1596 386 361 650 643 851 960 1000760 588 557 1264 1222

FIGS. 6-9 graphically illustrate the difference in pile capacitiesbetween electrokinetically conditioned soil samples exposed to anelectric gradient of 30 Volts DC/ft and substantially identical soilsamples (i.e., same composition and moisture content) not subjected toan electric gradient. As shown in FIG. 6, electrokinetically conditionedsoil samples having a 50% clay content and 35% moisture contentexperienced a 1043% greater pile capacity on average after 28 days, anda 620% greater pile capacity on average at the conclusion of the 256 daytest. As shown in FIG. 7, an electrokinetically conditioned soil samplehaving a 75% clay content and 12% moisture content experienced a 1170%greater pile capacity after 28 days, and a 489% greater pile capacity atthe conclusion of the 256 day test. As shown in FIG. 8, anelectrokinetically conditioned soil sample having a 75% clay content and17% moisture content experienced a 5392% greater pile capacity after 28days, and a 1900% greater pile capacity at the conclusion of the 256 daytest. As shown in FIG. 9, electrokinetically conditioned soil sampleshaving a 100% clay content and 35% moisture content experienced a 220%greater pile capacity on average after 28 days, and a 217% greater pilecapacity on average at the conclusion of the 256 day test.

FIG. 10 graphically illustrates the difference in pile capacitiesbetween substantially identical soil samples (i.e., 100% clay contentand 40% moisture content) exposed to different amounts of appliedelectric gradient (0 V, 1 V, 10 V, and 30 V/ft). Using the naturallyset-up (i.e., no applied electric gradient) samples as a baseline, thesamples exposed to a 1 V DC/ft electric gradient experienced a 24%greater pile capacity on average after 28 days, and a 73% greater pilecapacity on average at the conclusion of the 256 day test. The samplesexposed to a 10 V DC/ft electric gradient experienced a 100% greaterpile capacity on average after 28 days, and a 240% greater pile capacityon average at the conclusion of the 256 day test. The samples exposed toa 30 V DC/ft electric gradient experienced a 285% greater pile capacityon average after 28 days, and a 262% greater pile capacity on average atthe conclusion of the 256 day test.

A rapid moisture content test was conducted on every specimen on alltest days before performing a static load test. Table 17 shows amoisture content log at the beginning and the end of the testing period,in which slight reductions in the moisture contents of these specimenduring the course of the testing period are noted.

TABLE 17 Moisture Content Log Moisture content (%) Day P1 P2 P3 P4 P5 P6P7 P8 P9 P10  0 35 35 35 35 12 12 17 17 40 40 252 34 35 33 32 11 12 1515 38 38 256 34 34 32 31 12 11 15 15 38 38 Day P11 P12 P13 P14 P15 P16P17 P18 P19 P20  0 40 40 40 40 40 40 35 35 35 35 252 37 36 38 37 36 3834 34 32 32 256 36 36 38 37 36 33 33 34 32 32

The temperature of the specimens was monitored on a regular basis,especially during the period over which the electric gradient wasapplied. Table 18 shows a log of temperatures that was maintained duringthe testing period, in which the temperatures of the specimens wereobserved to be close to the ambient temperatures on the respective testdays, and not substantially affected by the application of the electricgradient.

TABLE 18 Temperature Log Temperature (° F.) Day P1 P2 P3 P4 P5 P6 P7 P8P9 P10 14 73 74 72 73 72 73 72 73 72 73 18 74 74 76 75 73 72 73 77 74 7322 73 72 74 74 73 75 73 75 72 72 28 72 72 72 73 73 73 72 72 73 72 30 6969 69 69 69 69 69 69 69 69 42 72 73 72 72 73 72 71 71 72 72 Day P11 P12P13 P14 P15 P16 P17 P18 P19 P20 14 71 71 72 83 87 72 78 79 80 82 18 7273 74 79 77 74 79 79 80 79 22 72 72 73 75 74 73 78 78 78 77 28 69 70 7075 73 69 78 78 75 74 30 69 69 69 69 69 69 69 69 69 69 42 72 72 73 72 7271 71 70 71 71

While various inventive aspects, concepts and features of the inventionsmay be described and illustrated herein as embodied in combination inthe exemplary embodiments, these various aspects, concepts and featuresmay be used in many alternative embodiments, either individually or invarious combinations and sub-combinations thereof. Unless expresslyexcluded herein all such combinations and sub-combinations are intendedto be within the scope of the present inventions. Still further, whilevarious alternative embodiments as to the various aspects, concepts andfeatures of the inventions--such as alternative materials, structures,configurations, methods, circuits, devices and components, software,hardware, control logic, alternatives as to form, fit and function, andso on--may be described herein, such descriptions are not intended to bea complete or exhaustive list of available alternative embodiments,whether presently known or later developed. Those skilled in the art mayreadily adopt one or more of the inventive aspects, concepts or featuresinto additional embodiments and uses within the scope of the presentinventions even if such embodiments are not expressly disclosed herein.Additionally, even though some features, concepts or aspects of theinventions may be described herein as being a preferred arrangement ormethod, such description is not intended to suggest that such feature isrequired or necessary unless expressly so stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure; however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Moreover, whilevarious aspects, features and concepts may be expressly identifiedherein as being inventive or forming part of an invention, suchidentification is not intended to be exclusive, but rather there may beinventive aspects, concepts and features that are fully described hereinwithout being expressly identified as such or as part of a specificinvention. Descriptions of exemplary methods or processes are notlimited to inclusion of all steps as being required in all cases, nor isthe order that the steps are presented to be construed as required ornecessary unless expressly so stated.

1. A method for increasing load capacity of a foundation pile installedin a ground material, the method comprising: embedding at least oneelectrode in the ground material at a predetermined distance from theinstalled pile; providing a direct current power source including atleast one cathode connection and at least one anode connection; securingone of the at least one cathode connections to the foundation pile;securing one of the at least one anode connections to each of the atleast one electrodes; and activating the direct current power source togenerate an electric gradient between the foundation pile and the atleast one electrode, the electric gradient being selected to directcharged soil particles in the ground material toward the foundationpile.
 2. The method of claim 1, wherein embedding at least one electrodein the ground material comprises embedding a plurality of electrodes inthe ground material at substantially equal predetermined distancesaround the foundation pile.
 3. The method of claim 1, wherein activatingthe direct current power source to generate the electric gradientcomprises supplying an electrical potential from approximately 1 volt DCto approximately 100 volts DC.
 4. The method of claim 1, whereinactivating the direct current power source to generate the electricgradient comprises generating an electric gradient of approximately 30volts DC/ft.
 5. The method of claim 1, wherein the charged soilparticles comprise clay particles.
 6. The method of claim 1, furthercomprising maintaining the electric gradient between the foundation pileand the at least one electrode for a period of at least approximately 48hours.
 7. The method of claim 1, further comprising measuring a moisturecontent of the ground material and adjusting one of an electricalpotential supplied by the direct current power source and a durationduring which the electric gradient is maintained based on the measuredmoisture content.
 8. The method of claim 1, further comprising measuringa clay content of a soil sample obtained from the ground material andadjusting one of an electrical potential supplied by the direct currentpower source and a duration during which the electric gradient ismaintained based on the measured clay content.
 9. The method of claim 1,wherein embedding the at least one electrode in the ground material at apredetermined distance from the installed pile comprises embedding theat least one electrode at a distance of at least approximately 3 feetfrom the installed pile.
 10. The method of claim 1, wherein embeddingthe at least one electrode in the ground material comprises embeddingthe at least one electrode to a depth of at least approximately one halfof the pile length.
 11. A system for electrokinetic conditioning of aninstalled steel foundation pile, the system comprising: a foundationpile embedded in a cohesive ground material containing negativelycharged particles; at least one electrode embedded in the groundmaterial at a predetermined distance from the foundation pile; a directcurrent power source having a positive terminal connected to thefoundation pile, and at least one negative terminal connected to each ofthe at least one electrodes.
 12. The system of claim 11, wherein the atleast one electrode comprises a plurality of electrodes embedded in theground material at substantially equal predetermined distances aroundthe foundation pile.
 13. The system of claim 12, wherein the pluralityof electrodes are embedded in the ground material at a distance of atleast approximately 3 feet from the surface of the foundation pile. 14.The system of claim 11, wherein the at least one electrode in the groundmaterial is embedded to a depth of at least approximately one half ofthe pile length.
 15. The system of claim 11, wherein the direct currentpower source comprises an adjustable direct current power source havinga maximum voltage of at least approximately 100 V DC.
 16. The system ofclaim 14, wherein the negatively charged particles comprise clayparticles.
 17. The system of claim 11, wherein the foundation pilecomprises steel.
 18. A method of loosening a conductive structureembedded in a ground material, the method comprising: embedding at leastone electrode in the ground material at a predetermined distance fromthe embedded structure; providing a direct current power sourceincluding at least one cathode connection and at least one anodeconnection; securing one of the at least one anode connections to thefoundation pile; securing one of the at least one cathode connections toeach of the at least one electrodes; and activating the direct currentpower source to generate an electric gradient between the foundationpile and the at least one electrode, the electric gradient beingselected to direct charged soil particles in the ground material awayfrom the foundation pile.
 19. The method of claim 18, wherein activatingthe direct current power source to generate the electric gradientcomprises supplying an electrical potential from approximately 1 volt DCto approximately 100 volts DC.
 20. The method of claim 18, wherein theconductive structure comprises a steel foundation pile.